Hair straightener

ABSTRACT

A hair treatment device comprising a base having means for collection to an electrical power supply, the base including a socket including a first electrical connector, tongs comprising a pair of limbs including at least one resistive of heating element, the limbs being connected by a hinge, the tongs further comprising a socket engaging portion including a second electrical connector, the socket engaging portion being adapted to releasably engage the socket so that the first electrical connector connects to the second electrical connector to connect the resistive element to the power supply, wherein the limbs are arranged to extend upwardly when engaged to the base.

This invention relates to an electric hair straightening or hair curlingdevice, particularly, but not exclusively, a hair straightener.

Conventional hair straighteners comprise a pair of heatable plateshaving heating elements in hinged limbs permanently attached to a powercable for connection to a mains supply. Such a device has a number ofdisadvantages. Permanent connection of the power cable can beinconvenient, hampering free use of the straightener.

The limbs of such prior devices are biased outwardly by a spring. Thisleads to a risk that a user may inadvertently grasp one of the heatedlimbs when picking up the device. Furthermore, the heated tongs may belaid down on a thermally sensitive surface or combustible material.

According to the present invention a hair treatment device comprises abase having means for connection to an electrical power supply, the baseincluding a socket including a first electrical connector,

-   -   the straightener body comprising a pair of limbs including at        least one resistive of heating element, the limbs being        connected by a hinge,    -   the straightener further comprising a socket engaging portion        including a second electrical connector, the socket engaging        portion being adapted to releasably engage the socket so that        the first electrical connector connects to the second electrical        connector to connect the resistive element to the power supply,        wherein the limbs are arranged to extend upwardly when engaged        to the base.

The present invention provides a cordless connection for a hairstraightening or curling device and confers several advantages overpreviously known devices. The heating limbs are prevented fromcontacting and damaging an underlying surface such as a polisheddressing table. Furthermore the upward arrangement of the limbs duringheating allows a higher power to be supplied without a risk of damage toan underlying thermally sensitive or combustible surface.

In a preferred embodiment a releasable latch is provided to retain thetongs in the socket.

In preferred embodiments both limbs include resistive elements and havea heated hair engaging surfaces. The width of each heatable surface maybe equal to or greater than 2.5 cm. Alternatively a narrower but thickerarrangement may be provided to afford a high thermal mass. In sucharrangement a higher thermal mass is provided than with a conventionalnarrow heating element for a hair curling or straightening device.

In preferred embodiments the opening of the socket extends upwardly fromthe base.

Resilient means are preferably provided to urge the limbs into an open,spaced apart orientation. The resilient means may comprise one or moresprings.

In a particularly preferred embodiment the limbs are partially closedwhen the tongs are engaged in the socket. The reduced separation betweenthe tongs in the partially closed position may be selected to make itdifficult for a user to accidentally insert a finger between the heatedlimbs while the tongs are engaged in the socket. This is particularlybeneficial with a relatively high powered device.

Partial or complete closing of the limbs when engaged in the socketconfers the additional advantage that heat loss from the heatingelements is reduced because radiant heat from one element impinges onthe other adjacent element. In preferred embodiments the two elements donot touch during the heating process to avoid a risk of over heating.

Use of heating elements with a width of 2.5 cm or more has the advantagethat a greater surface area is available to allow hair to bestraightened more quickly. Further the larger thermal mass means thatthe device can be used for longer periods without re-heating. Howeverheating of a higher thermal mass may be slower. In preferred devices inaccordance with the present invention a higher power capacity isprovided. This is possible as the limbs are safely stowed in a uprightposition during heating.

The heating element may comprise an aluminium core coated with a ceramicmaterial. A ceramic resistive heating element may be provided within thecore. This heating arrangement has a higher thermal mass thanalternative arrangements, allowing heat to be retained and alsopermitting use of high power resistive elements. Furthermore, ceramiccoated aluminium elements are cheaper and easier to manufacture thansolid ceramic elements. However, solid ceramic elements may he used ifdesired.

Aluminium cored heating plates having ceramic elements are beneficialbecause the heating time is quicker facilitating use in a cordless unit.

In the preferred embodiments of the invention the heating elements reacha temperature of 180-220° C. when the plates are in the open position.This temperature may be achieved within 1 minute. When removed from thebase the heating plates may maintain a temperature above 140° C. for atleast 4 minutes and re-heat from 140-200° C. within 20 seconds or lesswhen engaged from the base.

Use of a separate base allows provision of a digital display andconvenient actuation controls. This avoids the need for provision ofcontrols in the electrical connector lead. Furthermore the digitaldisplay in the base can be readily observed irrespective of theorientation or location of the tongs.

In an alternative embodiment a display may be provided in thestraightener. Use of wider plates than in conventional devices allowsthe read out to be located at an upper portion of the tongs if required,facilitating legibility of the display. In previous devices a displayhas been provided in the handle or making it difficult to observe thedisplay during use.

In preferred embodiments the socket securely engages the straightener tothat a secure electrical connection is provided. The socket may beaxially elongate, extending upwardly to provide a generally cylindricalsocket to receive the tongs.

The latch may be integral with one limb of the straightener so that thelatch may be released by urging the plates together against the actionof the spring. This avoids the need for a separate moving part. In apreferred embodiment the latch includes a tooth or otherwise shapedformation which engages an annular recess on the exterior of thecylindrical socket.

In the preferred embodiments the case may incorporate a rotatable spoolfor storage of the power supply cable.

The invention is further described by means of example but not in alimitative sense with reference to the accompanying drawings of which

FIG. 1 is a perspective view of a hair straightener in accordance withthis invention,

FIGS. 2 and 3 shows the base of a straightener in accordance with theinvention,

FIGS. 4 to 6 contain several views of the straightener body.

The hair straightener shown in FIG. 1 comprises a base (1) having amains power cord (not shown) extending to a plug (not shown), The cordextends from the rear of the base. A switch (3) and LED displays (4) aremounted on the front of the base to permit the device to be switched offor between on and standby positions and to indicate the status of thedevice.

A cylindrical socket (5) extends axially upwardly from the centre of thegenerally cylindrical base (1) and provides a recess (13) into which acorresponding shaped lower portion (6) of the straightener body or tongs(7) may be received and engaged to an electrical connection (4) betweenthe straightener (7) and power supply to a latch (8) integral with onelimb of the straightener (14) engages a formation (15) in the outersurface of the socket (5) to retain the tongs when engaged within thesocket. The latch (8) may comprise an arm having an inwardly facingtooth (16) or otherwise shaped projection to engage within an annularrecess in the exterior of the cylindrical sleeve (5).

The straightener body includes two plates (9),(10) joined for pivotedmovement at a lower hinge (11) and biased outwardly by means of a spring(not shown). When the straightener body is removed from the base theplates are urged apart by the spring to allow a users hair to beinserted between them.

In a preferred embodiment the limbs must be partially or completelyclosed to allow the lower portion (6) to be received within the socket(5).

Each plate (9),(10) includes a heating element electronically connectedto the base (6) of the body for connection to the power supply. Eachelement comprises a generally rectangular ceramic element having alateral width of 2.5 cm or more. Each element comprises an aluminiumcore coated with a ceramic material and having a ceramic resistiveelement within the aluminium core. Each element has a power consumptionof 40-80 W more preferably about 80 W in the steady state rising to apeak of 400-500 W when the element is heating from cold when firstturned on.

In use of the hair straightener the heated plates are manually pressedtogether, the base inserted into the socket and the plates released sothat the latch (8) engages the outer surface of the cylindrical sleeve(5). The power may then be turned on to heat the elements (11),(12) anLED display shows when the elements have reached the temperature. Thehandle of the straightener may then be grasped urging the limbs togetherto release the latch (8). Relaxation of the hand grip allows thestraightener to open for hair to be inserted. The tongs can then beclosed grasping the hair until the temperature of the elements dropsbelow the working temperature. The straightener is then reinserted intothe base to allow them to reheat.

1. A hair treatment device comprising: a base having means forconnection to an electrical power supply, the base including a socket,the socket including a first electrical connector; and a straightenercomprising: a pair of limbs including at least one resistive of heatingelement, the limbs being connected by a hinge; and a socket engagingportion including a second electrical connector, the socket engagingportion being adapted to releasably engage the socket so that the firstelectrical connector connects to the second electrical connector toconnect the resistive element to the power supply, wherein the limbs arearranged to extend upwardly when engaged to the base.
 2. A device asclaimed in claim 1, including a releasable latch to retain thestraightener in the socket.
 3. A device as claimed in claim 1,comprising two limbs each including a resistive element having heatablehair engaging surfaces.
 4. A device as claimed in claim 3, wherein thewidth of the heatable surface is equal to or greater than 2.5 cm.
 5. Adevice as claimed in claim 1, wherein the opening of the socket extendsupwardly from the base.
 6. A device a as claimed in claim 1, includingresilient means arranged to urge the limbs into an open spaced apartorientation.
 7. A device as claimed in claim 1, wherein the limbs arepartially closed when the straightener are engaged in the socket.
 8. Adevice as claimed in claim 1, wherein the heated plates comprise analuminium core coated with a ceramic material.
 9. A device as claimed inclaim L wherein the socket is axially elongate extending upwardly toprovide a generally cylindrical socket to receive the straightener. 10.A device as claimed in claim 1, wherein the latch is integral with onelimb of the straightener.